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Description:

I sometimes hear a buzzing noise during charging. Is something wrong?

No. The buzzing sound is mechanical resonance created by the switching of current through the circuit board and solid-state devices. This is normal and not indicative of a problem.

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Here’s a brief explanation on how to calculate the temperature compensated adjustments our controllers make to their charging voltages based on the ambient temperature changes.

The charging voltages listed in the controller operator’s manual are specified at a 25C standard test condition ambient temperature with a -.030V (@ 12V battery) adjustment per degree C change in temperature above or below the 25C reference. The (-) in front of the .030V indicates that voltage adjustment is inverse to the change in temperature. In other words, if the temperature increases above 25C, the controller decreases it’s charging voltage by -.030V per degree C rise above 25C and vice versa. An accurate measurement of the ambient temperature is required for calculating the the controller’s temperature compensated adjustment.

Example:

An ambient temperature of 35C = +10C increase above the 25C base temp = 10 x -.030V compensated adjustment = temperature compensated -.300V decrease in charging voltage.
Therefore, a 14.4V charging voltage specified in the manual @ 25C would be reduced to 14.1V @ 35C or increased to 14.7V @ 15C.

The compensation rate is doubled to .060V/C for 24Vnominal battery systems and quadrupled to .120V/C for 48V nominal battery systems.

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How do I calculate the effect of temperature compensation on the regulation voltage?

Refer to the accompanying document download, which includes compensation curves for most Morningstar Controllers, or refer to temperature compensation coefficient in the specifications section of the Operator’s Manual.

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Morningstar controllers have been designed to mount vertically. This is the orientation in which the heatsinks are most effective. Mounting the controller horizontally will reduce its passive cooling efficiency, but the risk of overheating will be determined by the ambient temperature and the power level at which the controller will be operating.

All efforts should be made to mount the controller vertically.

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Can I charge separate battery banks with one Morningstar charge controller?

Yes.  Refer to the document, “Charging Isolated Battery Banks – 1 Controller”.

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A wiring diagram for charging multiple isolated battery banks using multiple controllers and only one PV array.

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Most Morningstar controllers will take up to 5 minutes to realize that the solar input voltage is no longer present before transitioning into the ‘night’ state. The controller performs periodic day/nigh checks (about once every 5 minutes). Depending upon where the controller is in this cycle when the input is removed, it may take anywhere from 0-5min for the controller to turn off its Charging LED and go into the ‘night’ state.

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Our controllers are designed to charge lead-acid batteries which have different charging requirements than NiMh. Please DO NOT use our products with NiMh batteries, it is dangerous to do so.

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The internal switches of a controller, called MOSFETs or power transistors, switch current on and off to control solar current and load current. Because these components are in the power path, the controller will no longer be able to switch current if they fail.

Power transistors can fail for the following reasons:

• Over-voltage: lightning or other high voltage transients on the PV power cables.
• Over-current: too much PV for the controller or a short in the PV line pulls too much currentout of the battery through the controller.
• Extreme temperatures during charging.
• A premature failure of the component. The transistors are solid state devices that are manufactured in huge volumes with extremely low failure rates. However, no electrical components are 100% defect free and can pass test and then fail after a short period of time.
• Old age

Description:

Do Morningstar Controllers regulate according to SOC (State of Charge) calculations?

No. Morningstar Controllers regulate according to battery voltage setpoints. Because battery health and other factors affect charging over time, using voltage setpoints is a way to naturally track these changes and affords the user a complete understanding of the controllers operation. SOC calculations and algorithms may not be precise under all conditions and may leave the user with a “fuzzy” understanding of the workings of the unit.

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If no input source (solar) is connected to the charge controller, but there are other charging sources connected to the batteries, charge controller may still show a Green Flashing LED (indicating that the controller is in the absorption charging stage). The Green Flashing LED may appear on the Morningstar controller if the battery voltage is at or above the controller’s Absorption charging voltage setting. Although the controller is not delivering power to the batteries (because there is no input source present), the indication still appears. This is not an indication of controller malfunction.

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A higher voltage solar array (e.g. 24V nominal) can only be used with a lower voltage battery bank (e.g. 12V nominal) if the controller used is an MPPT controller.

PWM controllers CANNOT be used to charge a lower-voltage battery bank with a higher-voltage solar array. Please use an MPPT style controller if this is required.

Description:

The load outputs of multiple charge controllers can be wired together in parallel provided the following is true:

• The total load draw does not exceed the current rating of the LOWEST RATED CONTROLLER
• Isolating diodes are installed on each of the controller’s load outputs (if the controllers to not share a battery bank)

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All Morningstar controllers will automatically prevent reverse discharge of the battery back through the solar array during the night. No external diodes on the input of the controller are required.

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The following table shows expected quiescent current of the SHS controller for several battery voltages. The charging circuit consumes an extra 3.1mA.

Battery Voltage
Quiescent Current**
8 Volts
4.2 mA
10 Volts
5.1 mA
12 Volts
5.3 mA
14 Volts
5.5 mA
** Add 3.1mA during charging hours

Description:

Can I use a power source other than a PV panel to charge my batteries?

We do not recommend using a DC power supply with any of our PWM controllers. While they appear to be similar to PV modules in function, DC power supplies have considerably more output capacitance. Connecting a DC power supply to our PWM controllers may cause excessive heating and premature failure. MPPT controllers can be used for this purpose without issue. In addition, AC powered battery chargers are often the best option for systems requiring AC battery charging.

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Can I wire multiple controllers in parallel off the same PV array to charge different batteries?

Yes. Refer to the document, “Charging Isolated Battery Banks”. This can ONLY be done with PWM controllers. MPPT controllers cannot be used in this configuration.

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PWM is an acronym for Pulse Width Modulation. When the battery is recharged to regulation voltage, the controller will begin limiting the amount of current into the battery so that the regulation voltage is maintained but not surpassed. The method of regulating the current, referred to as PWM, pulses current into the battery with pulses of a varying width. Wider pulses allow a greater percentage of the input current to flow into the battery, narrower pulses restrict current to a lower percentage. Refer to the accompanying download,  “Why PWM?”, for more technical and detailed information concerning PWM charging.

Description:

The Load connection allows the user to wire DC devices such as fans, bulbs, or communication equipment directly to the controller. This allows the controller to disconnect the loads if necessary for protection of the controller, battery, or the loads themselves. This connection is optional and, as an alternative, the system loads can be wired directly to the battery bank.

Description:

All Morningstar PWM type controllers have a PWM switching frequency of ~300Hz.

Some Morningstar PWM controllers have a feature which will reduce the switching frequency to ~1Hz (called on/off charging). This on/off charging virtually eliminates switching noise (both radiated and conducted) and can be used when experiencing noise problems with 300Hz switching operation.

Current models with this on/off charging option are:

– SunSaver Generation 3

– SunSaver Duo

– ProStar PWM

– TriStar PWM

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Frequently Asked Questions about PWM battery charging are addressed.

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Other charging sources can be used in parallel with the Morningstar charge controller; you do not need to isolate the controller from the battery. For best performance when using other charging sources, ensure the charging source and Morningstar controller are set to charge to the same (or close) voltage. If the supplemental charging source is set to a higher charging voltage than the Morningstar controller, the Morningstar controller may go into a fault state temporarily when the battery voltage rises higher than the controller’s setpoint. The controller will automatically recover from this state when the battery voltage drops to a lower level.

Description:

We do not recommend wiring inverters to the load terminals of our products because of current in-rush on start up. Inverters typically have large amounts of input capacitance (for input filtering). When power is first applied, these capacitors can draw very large currents in the 100’s of amps, albeit for a short period of time. These current surges can stress our power transistors and will trip our short circuit protections. The inverter may start eventually after several attempts to reconnect from the short circuit condition, but this mode of operation is not normal. For this reason, we do not recommend wiring inverters directly. Many inverters have their own LVD circuitry and will not allow the battery to discharge too low. However, if the customer requires load control and LVD functionality, they can switch the inverter through a relay wired in series between the battery and inverter.

Description:

Yes. There can be as many Morningstar controllers as required in parallel on the same battery bank. For best performance, set each controller to as close a charge setting as possible. Since the controllers will not have direct communication with each other, it is not unusual to see the controllers transition between charging stages at different times. This is generally not a concern.

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The 2014/2015 Morningstar Product Catalog in English

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Short video highlighting Morningstar Corporation’s history and products.

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Morningstar Product Warranty

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The part numbers listed within are in compliance with Directive 2011/65/EC on the restriction of the use of certain
hazardous substances in electrical and electronic equipment (RoHS directives). This document also certifies that
the product declaration that has been provided by Morningstar Corporation is accurate.

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Documentation certifying that the Solar Home System conforms to the European testing requirements outlined by:

• EN 61000-6-2:1999 EMC Immunity, Ind. Environments
• EN 55024:1998+A1:2001 +A2:2003 Immunity
• EN 55022:1998+A1:2000+A2:2003 (Class B) EMC Emissions
• REACH EC 1907/2006 compliant
• Electromagnetic Compatibility Directive 2004/108/EC

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Whitepaper on Morningstar’s s high-level of innovation, R&D and engineering excellence.

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PDF file of the packed Weights and Dims of Morningstar products.